Method for producing carbon black



Feb. 21, 1939. J. .J. JAKOSKY ET AL METHOD FOR PRODUCING CARBON BLACK 5Sheets-Sheet 2 Filed March 2, 1937 S mnw W N as E M V K W 0 .E 7 J N 0 HT m1 mm a N frn w M W; wmm NN m mm 3 vmm ii I WM a N Q EMQZQSUK.NXWQEOQW 85 R9 m AT] Um v @WN A TTORNE Y.

Feb. 21, 1939.

J. J. JAKOSKY ET AL METHOD FOR PRODUCING UARBON' BLACK Filed March 2,1937 5 Sheets-Sheet 3 IN VEN TORS. Q JOHN J. JAKOSKY' I V F H xmwmm BY ffgi ATTORNEY. m x :2 v

1939- J. J. JAKOSKY ET AL 2,148,356

METHOD FOR PRODUCING CARBON BLACK Filed March 2, 1937 5 Sheets-Sheet 4INVENTORS. JOHN J. JAKOSKY VIc r012 F1 HANSON F Myw ATTORNEY.

Feb. 21, 1939. J. J JAKOSKY ET AL 2,148,356

METHOD FOR PRODUCING UARBON BLACK Filed March 2, 1937 5 Sheets-Sheet 5Patented Feb. 21, 193

' urn! METHOD FOR PRODUCING GARBON BLACK John J. Jakosky, Los Angeles,Calif., and Victor F. Hanson, Niagara Falls, N. Y., assignors toElectrohlacks, 1210., Culver City, Calif a cor- Wration of NeApplication March 2, 1937, Seriai No. 128,656

15 Cl- (Cl. Bit-dd) 'lhis invention relates to the production of"carbon-black, and particularly to methods involving the production ofcarbon-black in suspension in an organic or carbon-bearing liquidmedium, as tor example by electrothermal dissociation of such a liquid,and the separation of the carbon-black from such liquid medium byevaporation, and toapparatus in which such production and separation maybe carried out.

w This application is a continuation in part of our copendingapplication serial No.'653,799, filed Mar. 31, 1933.

The invention may be considered as comprising a method of heat-treatinga mixture of car- 35 hon-black and an organic liquid, such as an oil, toefl'ect a substantially complete separation of liquid and otherimpurities from the carbonblack and produce a carbon-blackhavin'gcertain characteristic properties which render it es- 20 peciallyadvantageous for certain purposes. such as rubber compounding. Suchmethod of treatment may be applied to a mixture of carbonblack andorganic liquid obtained by the direct production of carbon-black insuspension in such a liquid by electrothermal dissociation or othermeans, or to a mixture prepared by mixing on impure or inferiorcarbon-black or lamp-black product with a suitable organic liquid,the'principal purpose of the treatment in the latter case so being toalter or improve the properties of the black and obtain a. superiorgrade of carbonblack having more desirable characteristics for certainpurposes.

According to a preferred embodiment, the invention also comprises acomplete process-for production of carbon-black by'subjectingan oilorother carbon-bearing liquid to electrothermal' 1 treatment to producecarbon-black by dissociation of a portion of such liquid, causing such40 carbon-black to accumulate in' suspension in another portion of such.liquid to. form a carbonblackliquid-mixture of suitable concentration,and then subjecting such mixture to thermal treatment as above describedfor the production 45 of a liquid-free substantially pure carbon-blackof advantageous properties.

According to the methods of production of carbon-black by electrothermaldissociation of carbon-bearing liquids hitherto proposed, particularlyas exemplified in Jakowsky Patent 1,597,277 and Jakosky Patents1,673,245 and 1,872,297, the carbon-black was produced in a liquidmedium consisting principally of carbonbearing liquid from which thecarbomblack was 55 subsequently removed by filtration, centrifugalseparation, evaporation (following concentration of the carbon-black bysettling, filtration or the like) or by extraction with a suitablesolvent.

.It is thus seen that the production of a dried or liquid-freecarbon-black by the above de- 5 scribed methods may be divided into twomore or less distinct steps, namely, the dissociation 'oi the liquid toproduce a mixture or suspension of carbon-black in the liquid, followedby a separation step to recover the carbon-black in liquidm free form.

Although various methods of accomplishing this second step of separationhave been proposed, it has been found that the only practical andsatisfactory method for removal of the last portion of liquid from thecarbon-black is by evaporation. The methods heretofore proposed haverequired that the carbon-black be subjected to a separate mechanicalseparating operation, suchas centrifuging, filtering, or settling, priorto the evaporation or thermal drying operation, which not onlyintroduced an additional timeconsuming and laborious operation but alsocaused the loss or dissipation of a considerable proportion of the heatpreviously supplied to the mixture in the dissociation step, so that arelatively large amount of heat had'to be supplied for heating theconcentrated mixture to the temperature required for evaporation of theresidual liquid and tor evaporating such liquid.

It has been previously found desirable to conduct the dissociation ofthe carbon-bearing liquid in such a manner as to maintain a certainrelatively high concentration of carbon-black in the liquid, in order toimprove the efi'lciency of production and also to improve the operatingcharacteristics of the treaters and control the characteristics of thecarbon-black produced, and this desirable concentration'has beenobtained by regulating the rate oi throughput of the liquid 40 throughthe dissociation chamber, as disclosed in the pending application ofJakosky et al., Serial No; 397,841, now'Patent No. 1,912,373. If,however, the rate of throughput is maintained suiilciently low to causethe carbon-black to accumulate in the liquid to such an extent as toprovide the desired high concentration, the liquid undergoingdissociation becomes heated to a relatively high temperature, and inorder to prevent excessive evaporation and loss of volatile constituentsof the liquid due to such heating thereof, it has heretofore beenconsidered necessary to provide means for cooling the liquid undergoingdissociation, which cooling has normally been accomplished byrecirculation of the liquid in a closed circuit including thedissociation chamber'and a heat interchanger. This has resulted in thewaste of a considerable proportion of the energy supplied to theelectrothermal dissociation means. Furthermore, if it is desired toseparate the residual liquid from the black by methods involvingevaporation, ithas been necessary to again supply heat to thecarbon-black liquid mixture to effect such evaporation, as above pointedout.

An object of the present invention is, therefore, to producecarbon-black by electrothermal dissociation of a carbon-bearing liquidunder such conditions as to conserve the available heat from thedissociation means and utilize such heat in the drying operation.

A further object of the present invention is to provide a method inwhich the necessity for mechanical concentration of thecarbon-blackliquid-mixture is eliminated, by so conducting the processthat the liquid separation may be effected entirely by evaporation,without requiring the furnishing of a prohibitively large ambunt of heatfor this purpose.

In addition to the thermal inefficiency of the above-mentioned methodshitherto disclosed for production of a liquid-free carbon-black, thesemethods have been found unsuited to the production of carbon-black ofthe most advantageous properties for use in the rubber trade. Theextraction method produces a rubber black which possesses the properphysical and chemical characteristics, but this method of separation has.not been found economically feasible due to the relatively low thermalefficiency of the process and to the cost of operating an extractionprocess. Partial separation of the carbon-black from the liquid mediumby filtration or centrifugal treatment must necessarily be followed by amore complete separation, such as by evaporation or extraction, and,even though a filtration step I followed by an extraction step may becarried out at a cost which is not entirely prohibitive, the cost ismuch higher than in the process of the present invention. Furthermore,it has been found that, when certain type oils are treated for theproduction of carbon-black, a filtration or centrifuging step prior toevaporation causes a compacting of the carbon-black particles so that,upon ultimate drying of these particles, 9. carbon-black is producedwhich is quite difflcultly milled into rubber; a serious disadvantage asregards the use of the material in rubber compounding.

Removal of the residual liquid by previously proposed methods of directevaporation from the carbon-black-oil-mixture, or of evaporation from aconcentrated mixture obtained by filtration or centrifugal means, hasbeen found impractical for the production of the higher quality blacks,

for the reason that the residual carbon-bearing liquid is in part causedto sinter the carbonblack particles together, forming relatively densecoked particles or agglomerates of carbon which cannot be properlydispersed when milled into rubber. It has been found that thisobjectional "sintering is apparently due to the relatively long heatingperiod required in previous methods of this type, which results in theformation of certain gums or polymerization products from the residualcarbon-bearing liquid or from the vapors thereof. These products, inturn, cause a cementing of the individual carbon-black particles intorather large and diflicultly disintegrated agglomerates.

It is well known that unsaturated materials polymerize or condense atelevated temperatures to form products of heavier boiling point. Theseproducts are often called gums or resinous materials. These polymerizedor condensed products may be present in the carbon-black-oilmixtureundergoing the drying operation either due to their initial formationwhile the oil is undergoing treatment in the dissociation chamber, or totheir subsequent formation during the drying operation.

In the production of carbon-black by electrothermal dissociation ofoils, continued treatment of the oil undergoing dissociation causes anincrease in the unsaturation of this oil. The efllciency of conversionis increased with an increase in unsaturation, in accordance with apending patent application of J. J. Jakosky et al., Serial No. 584,894,filed Jan. 5, 1932, but at the same time this increasing unsaturationresults in formation of additional quantities of gummy materials in theoil by the action of the electric arc and oxygen reactions. The oxygenfor the latter reactions is supplied from dissociation of water vapor,dissolved air and other oxygen gases, etc., present in the oil. However,the amount of gums formed during the dissociation of the oil is usuallyof less serious consequence than the gums formed during the dryingoperation itself, as described in the following paragraph.

In the methods heretofore proposed for drying a mixture of carbon-blackand oil by evaporation, the drying operation necessarily extends over aconsiderable period of time. This results in the formation ofconsiderable quantities of gum and resinous materials. The conditions inthe drying operation itself favor the formation of such gummymaterialsdue to the relatively high unsaturation of the oil and the hightemperatures existing during the drying operation, The amount of gumformed is influenced by the rate of vaporization, as well as otherconditions existing during the drying operation. The longer the dryingtime, the greater is the quantity of gummy materials formed. The greaterthe unsaturation of the oil and the higher its end point, the greaterhas been the amount of gum formed in the final black produced. It hasbeen found that this percentage of gum can be greatly reduced by makingthe drying time as short as possible. Another factor which influencesthe percentage of gum formed may be termed the surface or contacteffect. It has been found that gum formation is increased when anunsaturated oil is evaporated to dryness in contact with the heatedwalls of a metal container and/or with large masses of carbon-black athigh temperature. Tests have shown that this percentage of gum can,therefore, be reduced by employing two conditions during the dryingoperation: .(1) a rapid or instantaneous evaporation of a relativelylarge proportion of the oil from the black; and (2) minimizing thecontact of the oil being evaporated, or the liberated vapors, with theretort walls or the partially dried black.

An important object of this invention, therefore, is to provide a methodfor eifecting substantially complete separation of oil or organic liquidfrom carbon-black, by evaporation, under such conditions as to causeextremely rapid or flash evaporation of a considerable portion of suchliquid and to also minimize contact of the liquid or the vapors thereofwith heated walls or with heated masses or particles of carbonblack, andthus minimize the formation of gums or other polymerization productsduring :uch operation.

Furthermore, the presence of oxygen, either during the electrothermaldissociation of the carbon-bearing liquid or during the subsequentdrying operation, also tends to increase the formation of gums or otherobjectionable polymerization' products. In addition, the presence ofoxygen or oxygen-bearing gases during the drying operation and thesubsequent cooling of the black is objectionable due to the tendency ofthe carbon black to take up or adsorb such oxygen or oxygen-bearinggases, which detract from the properties of the black, particularly whencompounded with rubber, it having been found that such adsorbed oxygenor oxygen-bearing gases tend to cause deterioration of rubber.

Consequently a further object of the invention is to provide a completeprocess for production of carbon-black by electrothermal dissociation,and subsequent removal of liquid and cooling of the dried black, underconditions of substantial exclusion of oxygen.

A further important object of the present invention is to produce acarbon-black of admirable characteristics for use as a filler,particularly in rubber compounding, by a method involving electrothermaldissociation of a carbonbearing oil or other suitable liquid, followedby separation of the carbon-black from the residual liquid and otherundesirable constituents in such manner that the advantageous propertiesof such black with respect to such use thereof are preserved.

A further important object of the present invention is to provideamethod for the production of carbon-black characterized by itssubstantial freedom from adsorbed or condensed gums, cementingmaterials, coking agents and hydrocarbons, and by its ease of properdispersion by milling into rubber.

Other objects of the invention will be apparent in the followingdescription, or will be specifically pointed out therein.

In the method of the present invention, a carbon-bearing liquid issubjected to electrothermal dissociation under superatmospherictemperature and pressure conditions, to cause dissociation of a portionof said liquid to form carbon in highly comminuted state dispersed inthe remaining liquid, and the resultingmixture or suspension of carbonin the remaining liquid is then subjected to a rapid evaporatingoperation at reduced pressure, to separate said remaining liquid fromsaid carbon by evaporation thereof at a pressure lower than thatmaintained during such dissociation, and preferably at a pressure not inexcess of atmospheric, to produce substantially pure, liquid-free carbonin-the physical state commonly referred to as carbonblack.The'above-mentioned dissociation may be carried out by maintaining anelectric arc discharge between electrode submerged within a body of suchliquid, and the evaporation of the remaining liquid from the carbon ispreferably effected largely or wholly by flash-evaporation obtained bydischarge of the mixture of carbon and liquid, while still at a hightemperature, from the superatmospheric pressure under which thedissociation is conducted, into a drying chamber maintained atrelatively low pressure. This flash-evaporation step may be followed bya further heating operation for the purpose of removing residualvolatiles or liquids, if any,

which may be present in said carbon-black after such flash-evaporation.

The dissociation step is preferably conducted under such temperature andpressure conditions as to provide for flash-evaporation of substantiailyall or a major portion of the residual carbon-bearing liquid from saidcarbon-black by the agency of the sensible heat of said liquidv and saidblack, whereby a relatively small amount of additional heat is requiredfor complete drying of said black following said flash-evaporation step.

Another important feature of the invention is that the dissociation ofthe carbon-bearing liquid may be carried out under conditions whichallow for maintenance of high concentration of carbon-black in theliquid, which has hitherto been unattainable without excessive heatlosses. According to this invention the electrothermal dissociation ispreferably continued until a concentration of between 5 and 15 per centof carbon-black by weight is obtained in the carbonbiack-liquid-mixture, and the mixture is maintained during suchdissociation under a sumciently high pressure to permit substantiallyall of the heat delivered to the liquid by the electrothermaldissociation means to be retained in the liquid without causingexcessive vaporization thereof in spite of the relatively low throughputof the liquid which is necessary to provide this relatively highconcentration, and the heat thus retained in the oil is subsequentlyutilized in the evaporation of the remaining liquid from the mixture..After completion of the drying and heat treatment of the carbon-black,said black is subjected to a cooling operation, preferably in anenclosed chamber.

Another-important feature of the invention is that the heat treatment ofthe black following flash-evaporation is carried out under conditions ofprogressively increasing temperature, and the vapors evolved during theflash evaporation and during said heating operation are removed from thecarbon-black in such manner as to prevent contact of' said vapors withcarbon-black particles, or with heated wall surfaces, which are at ahigher temperature than said vapors. This result may be attained, forexample, by passing the carbonrblack, following flash-evaporation,longitudinally through a drying chamber of progressively increasingtemperature, and withdrawing evolved vapors longitudinally of saidchamher in a direction opposite to the direction of travel of thecarbon-black. If desired, the vapors may be positively removed from thechamber adjacent the position of evolution thereof, as by means of aperforated vapor outlet pipe extending longitudinally within the dryingchamber.

The process of the present invention is preferably carried out underconditions which provide for substantially complete exclusion of oxygenduring all stages of the process. This may be accomplished bymaintaining the liquid undergoing dissociation, as well as thecarbon-black in all the stages of production, in an atmosphereconsisting principally of gases evolved by the electrothermaldissociation, or other oxygen-free gases. Such oxygen-free gases will bereferred to hereinafter as inert gases. It has further been founddesirable to conduct the drying and cooling steps of the carbon-blackproduction cycle in the presence of a countercurrent stream of such aninert gas, whereby removal of volatiles from the carbon-black may befacilitated by a reductionof the partial pressure of such volatilesduring the drying step and the carbon-black may be protected fromcontact by oxygen-containing gases during the cooling step. In thuscooling the carbonblack, the material is cooled in the presence of theinert gas to temperatures far below oxidation temperatures; 1. e., totemperatures at which it is feasible to package the product. Preferably,the product is cooled in the presence of oxygen-free gas to atemperature not higher than 150 C. and the cooled product is sealed insubstantially airtight packages without exposure to the air. Forexample, the carbon-black, dried under an oxygen-free atmosphere, may becooled in the same atmosphere until cooled to room temperature (1. e.about 1530 C.). Preferably, the so-cooled black is then packaged in airtight containers while avoiding contact of the air therewith. By thuskeeping the black in an atmosphere of inert gas, the adsorption ofoxygen therein is prevented and a superior product .(e. g., for rubbercompounding) is produced.

The cooling procedure may, if desired, include the introduction of asuitable treating agent in vapor form to the cooling black so that saidblack is caused to cool in the presence of such an agent, as and for thepurpose hereinafter set forth.

The above-described method is preferably carried out continuously, bycontinuously supplying a carbon-bearing liquid to the dissociationchamher and continuously removing the carbon-blackliquid-mixturetherefrom and subjecting the same to flash-evaporation followed byheatin and cooling, as above-described, and the gaseous dissociationproducts formed by the dissociation reaction (which may comprisehydrogen, methane, acetylene or the like) are preferably alsocontinuously withdrawn from the chamber and passed in heat exchangingand scrubbing relation to the in-coming liquid, in such manner that thesensible heat of such gaseous products is utilized in heating suchliquid, and in such manner that any carbon-black or condensiblecarbonbearing liquid products carried by such gaseous products will becaused to enter the 'in-coming liquid stream and be thus returned to thedissociation chamber.

The carbon-black produced by the method herein described ischaracterized by certain physical properties, such carbon-black beingpreferably obtained in the form of small, loosely-bonded aggregates ofcarbon particles which may be readily crushed or milled into animpalpable powder, but which are possessed of sufficient physicalstrength to allow reasonable handling thereof without excessive flyingor floating of the finer particles. The carbon-black obtained bypractice of the present invention is particularly characterized by adefinite vesicular or "honey-comb" structure of the individualaggregates above-referred-to.

The accompanying drawings illustrate apparatus in which the method ofthe present invention may be carried out, and referring thereto:

Fig. 1 is a diagrammatic representation of one form of apparatus whichmay be used for practice of the complete invention;

Fig. 2 is 'a vertical section, partly in elevation, of the dissociationchamber and dryer-feed portions of the apparatus, on an enlarged scale;

Fig. 3 is a sectional detail of the form of carhon-black treater ordissociation chamber shown in Fig. 2, taken on line 3-4 therein;

Fig. 4 is a sectional detail of an alternative form of feeding devicefor the dryer;

Fig. 5 is a partly vertical section and side elevation ofthe dryingapparatus shown diagrammatically in Fig. 1;

Fig. 61s a transverse section thereof, taken on present invention;

Figs. 9 and 10 are sectional details thereof, taken on lines 9-9 andiO-lfl, respectively, in. Fig. 8;

Fig. 11 is a partly vertical sectional elevation of an alternative formof dryer means, in which the drying operation is divided into threeseparate stages;

Fig. 12 is an enlarged vertical sectional detail of the upper endportion of the first stage of the dryer shown in Fig. 11;

Fig. 13 is a transverse view taken on line l3--I3 in Fig. 12;

Fig. 14 is an enlarged longitudinal section of a portion of the dryershown in Fig. 11, showing a form of feeding means which may be usedintermediate the several stages.

Fig. 1 shows a schematic layout of the various elements of apparatuswhich may be used in the practice of the method of the presentinvention, and pertains particularly to the manner in which thevariouselements are correlated to obtain the desired heat economies ofoperation; referring thereto: i is a storage receptacle for thecarbonbearing liquid (such a liquid being hereinafter referred to asoil"), connected by a conduit 2a to a scrubber and heat exchanger 2which is in turn connected to an electrothermal dissociation chamber 3by means of an oil conduit 30 and a vapor conduit 3b. Said scrubber isadapted to receive gases from the chamber 3 through the conduit 3b andheat the oil supplied to said chamber from the storage receptacle 1, sothat most effective utilization of the thermal energy in these gases maybe had and at the same time cause the principal proportion ofcondensible vapors in said gases to be absorbed in the entering oilstream and returned to the dissociation chamber. Any carbon-blackcarried over from'the dissociation chamber by the gas stream will alsobe removed from such gases by contact with the oil stream in saidscrubber and returned to said chamber. The cooled and substantiallyclean gas is preferably conducted to a suitable gas-holder or gasometer4 through a suitable conduit 4a.

Within the dissociation chamber 3 the oil is subjected to electrothermaldissociation which results in the formation of carbon-black within theoil, and the mixture of carbon-black and oil (hereinafter referred to asCarbon-Black-Oil- Mixture", and abbreviated CBOll/l) is passed underpressure and at an elevated temperature to the inlet end of a suitablekiln-dryer 5, into which it is flashed and the principal proportion ofthe liquid allowed to evaporate substantially instantaneously. The kiln6 is preferably of the rotary tube type and is provided with means forapplying additional heat to the fiashed" carbon-black, in such mannerthat the partially dried carbon-black is allowed to progress from theinlet end into and through a progressively hotter drying zone or section3| and thence through a cooling zone or section 32 into a suitablereceiving hopper 8. Suitable means such as a screw conveyor la may beprovided for removal of the cooler carbon-black from the hopper 6 tosuitable storage means 7, from which it may be withdrawn by conveyingmeans 1b and delivered to suitable packaging means, if desired. Thepresent invention also contemplates subjecting the cooling carbon-blackto the action of an inert gas and provision is made, as at 8 and 8a, forthe introduction of the inert gas. Likewise, a suitable treating agentas hereinafter described may be combined with the cooling black, e. g.by introducing said agent at inlet 8.

The vapors resulting from the flash-evaporation of the CBOM and thesubsequent drying of the carbon-black are withdrawn from adjacent theinlet end thereof as at 9, and are passed to a cooling condenser H,wherein the condensible portions of such vapors are separated andreturned to the oil supply means, for example through the conduit l2 tothe line 2a, and the non-condensible gases are passed through conduit 4bto the gasometer. In some cases, the liquid collected in condenser llmay contain a liquid immiscible with the condensed oil vapors; forexample, if a treating agent is introduced at 8 which is immiscible withthe condensed carbon-bearing liquid, and in such cases, a suitableseparator l3 may be connected to conduit l2, for example, as shown, toprovide for the separation of any suchimmiscible liquid. In the eventthat it is considered desirable to operate the dryer 5 at.asub-atmospheric pressure, a suitable pump line coming from the condenserll. It may also be found desirable to provide a suitable pump in theconduit It, for example as shown at I2a, to facilitate return of thecondensed vapors from condenser H or separator l3 to the oil line 241,this pump being of particular advantage when the condenser l l isoperated at a sub-atmospheric pressure.

In order to take advantage of the latent heat of the vapors dischargedfrom the dryer, this thermal energy may be utilized to heat the oilsupplied to thedissociation chamber. For this purpose, the vapors fromthe dryer 5 may be passed directly into the scrubber and heatexchanger2, as for example by means of a conduit 9a leading from the conduit 9 tothe conduit 3b. A suitable pump 9b is preferably provided in the conduit9a to facilitate transfer of the vapors from the conduit 9 to theconduit 3b.

It may also be found desirable or convenient to provide a pump in theline leading from the oil storage through the heat exchanger to thedissociation chamber, so that oil may be continuously .forced into saidchamber independent of the pressure maintained therein. This pump may belocated in the oil line 2a entering the heat exchanger, as at l5, orthis pump may be put in the oil line 3a adjacent the dissociationchamber 3 if desired.

Figs. 2 and 3 show the dissociation chamber 3 in more detail. Saidapparatus is shown as being of the type shown and described in thepending application of Jakosky, Serial No. 588,146 now U. S. Patent No.1,965,925, and comprises essentially a casing or container 2| providedwith a plurality of electrode units mounted within said casing and eachcomprising a relatively fixed and one or more relatively movableelectrodes, there being, in the form shown, three of such units,indicated at E1, E2 and E3.

Three electrode units are shown for the reason that such a number, or amultiple thereof, is

the kiln 54 may be connected in the vapor 22a constitutes an arcing faceformed as asurface of revolution, of relatively small width inproportion to its circumferential length, and lying in a planesubstantially perpendicular to its axis, and a relatively rotatableelectrode holder 23 mounted on a rotatable shaft 24 and having one ormore radial arms 23a each carrying a rodshaped electrode 25 ofrelatively small crosssection disposed above the correspondingelectrode, surface 22a and inclined rearwardly with respect to thedirection of travel of said electrode at a' suitable trailing angle. Theelectrodes 22 and 25 may be formed of any suitable conducting material;for example, suchelectrods may advantageously consist of carbon and maybe manufactured in the same general manner as other carbon electrodescommonly employed for maintaining electric arcs. Power supply to the.respective electrodes may comprise suitable connections to the severalelectrodes whereby electrical energy at the desired potential may besupplied thereto after the manner shown. It has been found convenient toinsulate the ring electrodes 22 from the casing 2| and connect theseelectrodes each to a separate phase of a three-phase power supplysystem, which may comprise a suitable transformer T, through suitablereactances R and R or the like, while connecting the rotating electrodesto ground as at G through the common shaft upon which they are mounted,through the casing 2|, as shown in Fig. 2.

It will be understood that suitable driving means, for example, avariable speed motor 24a, are provided whereby rotation of the shaft 24may be had, and that adjustment means, such as is indicated at 24b, areprovided for determining, maintaining and-adjusting the separation ofthe rotatable electrodes from the fixed electrodes through longitudinalmovement of the shaft 26. The above mentioned means, for the purpose ofthe present description, may be substantially as shown and described inthe abovereferred-to pending application, Serial No. 588,146.

At the concentrations of carbon-black contemplated in the presentinvention, it is diflicult to accurately govern by means of a valve thefeed of the CBOM from the dissociation apparatus to the dryingapparatus. Means are therefor provided for properly controlling thisfeed, and the form of. feed-control means shown herein may comprise oneor more monte-jus devices such as indicated at 26 and 21, provided attheir lower ends with connection as at 26a and 21a to the dissociationchamber 3, and at their upper ends with pressure fluid connections 26band 21b. The above-mentioned connections are provided with suitablev'alves indicated by prime marks on the respective reference numerals,as at 26a, etc. A line 28 connected to the bottom of both of themonte-jus devices through valved connections 28a and 28b leads to theinlet end of the dryer 5. The monte-Jus devices 26 and 21 may beprovided with valved vents 26c and 2'|c at their upper ends.

When it is desired to feed CBOM into the 75 tion3| is preferably ofdryer, one of the monte-ius devices,for example 28, is filled with CBOMfrom the dissociation chamber 3 by opening the valve 260., with thevalves 21a, 28a, and 26b closed. As the pressure in the dissociationchamber forces the CBOM into the-monte-jus, the vent 26c may be crackedslightly so as to allow the monte-jus to fill, and the vent valve 26cand valve 26a then closed. The 'yalve 21b is then opened to the desireddegree to admit a suitable-pressure fluid, such as a compressedhydrocarbon gas to the monte-jus 23, and the valve 28a opened to allowthe CBOM to be forced out through the line 28 to the dryer. While themonte-jus 26 is being emptied into the dryer, the monte-jus 21 may befilled as above described, and the respective monte-jus devices may bealternately operated, so that a substantially continuous withdrawal ofCBOM from the dissociation chamber 3 and a substantially continuoussupply of CBOM to the dryer is maintained.

The dryer 5 may comprise an elongated tube inclined downwardly from theinlet to the outlet end, provided with external heating means for theupper or inlet end portion, said heating means being preferably sodisposed as to provide a zone'of continuously increasing temperaturedownwardly from the inlet end to the lower end of said portion. Thedryer, as shown in Figs. 5 to '7, may comprise an upper or heatingsection 3| and a lower or cooling section 32. The upper secgreatercross-sectional area than the lower section 32, so that the carbonblackin descending through the upper section will occupy a relatively smallproportion of the cross-sectional area of said sectio whereby minimumcontact of the released vapors with said carbon black is obtained, whilecausing the carbon-blackto occupy a relatively large proportion of thecross-sectional area of the lower section 32, thereby assuring bettercontact between the material and the dryer walls to facilitate transferof heat from the carbon black to said walls, and better contact betweenthe carbon black and the treating vapor or gas which may be passedupwardly through said lower section, as subsequently described. Theupper section 3| is provided with heating means which may comprise aburner 33 directed into a fire-box 34 provided with a heating chamber orfine 35 built around the section 3| and having a stack 33 at the upperend thereof. This construction provides for maintaining a downwardlyincreasing ing section 3| in such manner that the carbonblack descendingthrough said section is exposd to continuously increasing temperatureduring its downward passage from the inlet end to the lower end of saidsection. The dryer may be rotatably mounted on suitable bearings 31a,31b and 310, which may rest on suitable supports 33.

Referring particularly to Figs. 2 and 4, the upper end of the uppersection 3| is provided with .a tubularextension 39, preferably ofreduced diameter, on which is mounted a sprocket ll through which thedryer may be rotated by means of a chain 42 and a motor. Said extension33 extends within a fixed housing .or vapor outlet chamber 44', provided'with'a vapor outlet connection 3 leading to the condenser N (Fig. 1).The CBOM supply line 23 is connected to an inlet pipe 46 which extendslongitudinally through housing 44 and extension 39, said inlet pipe preferably terminating within the upper end portion of the dryer section 3|in position to discharge the CBOM'. into said section, preferablytemperature in the heattoward the side-walls thereof, as by means of anozzle shown at 41. The chamber 44 is preferably also provided with avapor-tight connection with the tubular extension 39, as by means of astufring-box 48.

The CBOM feeding means shown in Fig. 4 may,

if desired, be used in place of the plain nozzle 41, so that a gasrelatively inert at the temperatures involved, may be used to atomizethe CBOM into the dryer. This alternative form of feeding means maycomprise an atomizing gas line 50a extending longitudinally through thehousing ll and the tubular extension 33 and provided with a dischargenozzle 501) at its inner end, and a CBOM discharge line 500 extendingwithin said line 50a and terminating adjacent said nozzle. Thisarrangement provides for introduction of CBOM into the dryer through thedischarge line We simultaneously with the introduction of atomizing gasthrough the nozzle 50b, whereby said CBOM is atomized in itsintroduction to the dryer.

If desired, a super-heated gas may be introduced to the CBOM dischargeline 23 at any suitable point for example such as at 23c, as shown inFig. 2. It will be comprehended that any suitable type of gaseous-agentmay be introduced in this manner, for example, hydrogen, methane. orother suitable gas, such as that produced during the dissociation of theoil and consisting in general of a mixture of hydrogen and gaseoushydrocarbons. In some cases, steam may be introduced at this point,although we prefer, in general, to use an oxygen-tree gas.

As shown in Fig. 5, the lower end of the dryer may be provided with asuitable closed hopper t, Y to receive the dried carbon-black, thehopper being conveniently providedwith a clean-out manhole 6a wherebythe black may be removed at intervals, as desired. A suitable form ofpack- 0 ing or'stufnng-box' means 31; is preferably provided for thehopper. :so that escape of gases from the dryer or entrance of airthereinto isprevented. It will be understood that a suitable continuousdischarge means such as is shown at In in Fig. 1 may alternatively beprovided for the hopper, if desired, for continually removingmaterialfrom said hopper and conveying the same to a closed storagereceptacle 1. An inlet pipe 3 may be provided, extending-upwardly ashort distance into the lower section 32 for introduction of a treatingagent or an inert gas into the drying zone. I

At the junction of the sections 3| and 32, where a change in diameter ofthe two sections takes place, suitable causing the dried carbon-black toenter the tube 32 in such manner as to prevent accumulation of driedblack in contact with the side walls of the heating section at the lowerend thereof.-

Such means, as shown in Figs. 5 to 7, may conveniently comprise a baiiieplate 3|a disposed diametrically, across the lower end of the section 3|and two oppositely inclined scoop-plates 3|b and 3|c disposed atopposite sides of the plate 3|a. The rotation of the dryer (in thedirection indicated by the arrow in Fig.6) will cause the scoop-platesto gather such dried black as may fall into the lower portion of theapparatus at the point indicated by the arrow Z and lift the samethrough a portion of a revolution of the dryer and then cause the blackto pass by gravity into the upper end of section 32.

Fig. 7 shows a flexible coupling device 5| which may be provided for thepurpose of securing the respective dryer sections 3| and 32 togetherdurmeans are provided for 'due to heating effects.

. to the upper end of the ing rotation of the dryer, while taking careof any eccentricities in the aligmnent of saidsections Said couplingmeans may comprise a spherical bearing member 52 secured section 32disposed within a housing 53 secured to and projecting axially from theend of the section 3i and provided at its outer end with a flange 53a,said housing and said bearing member 52 being secured togetherfrictionally by means of packing material 54 which is kept undercompression by means of a flange 55 bolted to the flange 53a, so thatupon rotation of the section 3| by means of the motor 43, the frictionalengagement of the packing material between the housing 53 and thebearing member 52 will cause a rotation of the section 32. A sumcientamount of play is left between the section 32 and the end oi the section3!, as at 56, and between the flange 55 and the section 32, as at 56a,so as to accommodate any misalignment of the one section with respect tothe other section. The bearing 31a at the lower end'of the section 32may be of such construction as to take up any thrust in said section,and preserve the longitudinal position of said section, while the upperbearing 31b on section 32 and the bearing 310 on section 3| may beallowed to float so that longitudinal expansion of the dryer w'illoccasion no bearing difliculty. As the dryer expands the tubularextension may slide with respect to the housing ,through thestuiling-box 48.

In the. practice of the present invention, a carbon-bearing liquid oroil is placed in the storage receptacle I and a supply of this oil isconveyed to the dissociation chamber 3 through the heat exchanger 2.Examples of carbon-bearing liquids or oils well adapted for practicingthe present invention are kerosene and similar petroleum fractions andvarious other liquid petroleum products, such as "Edeleanu extract.Edeleanu extract, a product obtainable by the well known Edeleanuprocess" for refining hydrocarbon oils, e. g, kerosene, is a liquidproduct obtained from the oil by the selective solvent action of liquidsulfur dioxide. As above mentioned, a suitable pump or the like maybeplaced in this oil supply line so asto provide supply of oil to thedissociation chamber under any operating pressure established in saidchamber. With the electrodes 22 and properly energized, an electric arcwill be established between the arcing surfaces of said electrodes,causing dissociation of the carbonbearing liquid or oil. Thisdissociation results in the formation of carbon-black in the liquid bodyin finely dispersed state and also results in formation of fixed gasessuch as acetylene, methane, hydrogen, and other gases, which are passedfrom the chamber to and through the heat exchanger 2, and thence to thegasometer 4 for storage. The gases evolved from the liquid undergoingdissociation in the dissociation chamber will enter theheat exchanger ata relatively high temperature and will necessarily carry an appreciablequantity of vaporized liquid from said chamber as well as, under someconditions, an a ppreciable proportion of carbon-black suspendedtherein. For this reason the heat exchanger is preferably of suchconstruction as to efiect a "scrubbing of these evolved gases wherebythe condensible constituents and suspended carbon particles are returnedto the oil stream and thus caused to re-enter the dissociation chamber.

The electric arcs within the dissociation chamber 3 evolve considerableheat inasmuch as but a portion of the electrical energy supplied to saidand the heat thus evolved v proximately 13% carbon-black dissociation oithe oil, is utilized to increase the temperature of the liquid bodywithin the chamber to a suitable super-atmospheric tempera ture.According to the preferred embodiment of the present invention, themixture of carbonblack and dissociable liquid is maintained under asuper-atmospheric pressure withinthe dissociation chamber, suflicient toprevent boiling of the liquid at the temperature of operation, whichtemperature is preferably about .equal to or in excess or the boilingpoint of the heaviest fractions of the liquid, at the pressure at whichthe subsequent flash-evaporation is conducted.

When a dissociable liquid such as kerosene is used for production ofcarbon-black according to the present invention it has been foundpractical to maintain a gauge pressure of 50 lbs. per sq. in. on thedissociation chamber, which pressure will allow of an averagetemperature of in the neighborhood of 500 to be attained by. the CBOMwithin the treater without excessive gasification or vaporization of thedissociable liquid.

The dissociation is continued until a suitable concentration of carbonblack is realized in the mixture, the upper limit of this concentrationbeing-limited principally by the fluidity of the mixture. In general,the liquid is preferably caused to remain in the dissociation apparatusuntil the concentration of carbon-black therein has reachedapproximately the maximum value consistent with the above mentionedlimitations. When kerosene is used as the dissociable liquid, thisconcentration may conveniently reach apunder the temperature andpressure conditions above outlined, while concentration above thisamount has been found to cause surface leakage on insulators within thedissociation chamber.

When a suitable concentration of carbon-black has been attained in themixture within the dissoarcs is consumed in actual ciation chamber, thismixture may be withdrawn from the treater and introduced to one of thesupply of fresh liquid to the treater may be so balanced as to maintaina substantially continuous flow of liquid to and CBOM from. thistreater.

Referring to Fig. 2, when one monte-jus is filled with CBOM to thedesired extent, the valves 26a, 26b, 26c, 21a, 21b, 210, 28a and 28b areproperly set so as to obtain delivery of CBOM from the monte-jus to thedryer, suitable fluid pressure being applied to the monte-jus-so as toforce the CBOM through the inlet line 28. It

' will be understood that the CBOM is preferably maintained under theabove mentioned superatmospheric temperature and pressure conditions upto the amount of discharge thereof into the dryer section 3| and themonte-jus devices and the necessary supply .pipes may be provided withsuitable insulation for this purpose. When the CBOM is discharged intothe dryer, which is maintained at a relatively low pressure preferablynot in excess of atmospheric, the mixture will flash, causing avaporization of the major portion of the volatile matter in saidmixture.

It will be comprehended that, dependent upon the concentration ofcarbon-black and the temperature and pressure at which the mixture isflashedf, the degree'of vaporization of the volatile constituents ofsaid mixture may be controlled within rather wide limits. It has beenfound disadvantageous to cause a complete vaporization of saidconstituents in the flashing operation for the reason that thecarbon-black thus obtained is in the form of a very flne, a1- mostimpalpable powder, which is not only difficult to collect but is notpreferred by the rubber trade inasmuch as it is very disagreeable tohandle. In order to produce a carbon-black, therefore, which is properlydried yet in suitable physical condition, the present inventionparticularly contemplates flashing the CBOM under such temperature andpressure conditions and at such carbon-block concentration that theflash evaporation thereof results in the formation of lumps orloosely-bound agglomerates of carbonblack particles and a very smallproportion of dust or substantially none at all. According to thepreferred method of drying the CBOM, these loosely-bound agglomerateshave a honeycomb or vesicular appearance and structure similar to thatof lava or other material which has solidified while evolving gases orwhich contained considerable quantities of gas during solidification.This honey-comb structure of the dried material allows it to be brokendown with very slight mechanical pressure and this feature is ofparticular advantage in providing for better incorporation anddispersion of the material in rubber. The size of these agglomerates ispreferably maintained on the order of a few millimeters in diameter, forexample from 0.75 to 10 mm. in

' diameter.

the volatile constituents.

When the mixture is flashed under such conditions as to produce lumps ofthe size and type above described it has been found desirable to subjectthe same to a further drying operation to remove the residual liquid andgaseous material. According to the preferred'form of the invention,therefore, the CBOM produced as above outlined is flashed into asuitable heating zone under such conditions as to produce the abovedescribed lumps and therein and thereafter exposed to sufllcientadditional heating to completely remove the major proportion ofvolatiles therefrom,

When a dryer of the type herein disclosed is used, the CBOM is flashedinto the upper section 3i and is allowed to pass downwardly through thissection upon rotation thereof after the manner of the well known typesof rotary dryers. Heat is applied to the exterior of this section of thedryer and the carbon-black is gradually brought to a temperaturesufllcientto drive out The temperature of the black at the lower end ofthe dryer section 3| may advantageously be as high as I300 F. One of theparticular features of this type of dryer is that the flashedcarbon-black is moved downwardly through the dryer and is graduallybrought to maximum temperature, while the gaseous products are drivenupwardly past the descending black in such manner that these gases arecaused to contact carbon-black and surfaces which are at a lowertemperature than that of the gases whereby decomposition of these gasesby such contact is minimized to a' great degree, minimizing i formationof the aforementioned condensation or polymerization products whichcause a sintring of the material.

After passing through the dryer section 31 the black is fed into thedryer section 32 by means of the arrangement shown in Figs. 6 and -'7and is progressively cooled during its passage through said section 32,and then discharged into the hopper 6 from which it may be withdrawn tostorage or packaging as desired. In cooling section 32, the productis-cooled to'a temperature well below its ignition temperature in thepresence of inert gas introduced at 8. If desired, section 32 may be ofsufflcient length and provided with suitable cooling means to cool theblack to a temperature suitable for packaging, i. e., to 150 C. orlower. Alternatively, if the product entering hopper 6 is too hot forpackaging, further cooling may be eifected in hopper 6 and in coolingconveyor Ia, while under an oxygen-free atmosphere obtained byintroducing an inert gas at to.

Storage receptacle la is closed to the air and the material therein ismaintained under an inert gas atmosphere, by reason of the inert gas fedin at 8a. Thus, the carbon-black may be dried and cooled, e. g. to roomtemperature and stored, under substantially oxygen free conditions. Asthe black cools, it tends to adsorb the inert gas and consequently thecooled product is substantially free from adsorbed oxygen. This cooledproduct, having a temperature not in excess of about 150 C. andpreferably cooled to about 15-30" C., will adsorb oxygen only veryslowly if exposed to the air. Hence the material withdrawn fromstorage Imay be packaged readily by usual methods, using reasonable care to avoidprolonged exposure to the air. To maintain the high quality of theoxygen-free material, it should be packaged in air-tight containers withlittle or no air space in each container.

The CBOM may be mixed with other materials before introduction into thedryer system, if desired, for example the CBOM may be flashed into thedryer by atomization thereof with a suitable inert atomizing gas, anarrangement such as shown in Fig. 4 being used for this purpose. Thisarrangement obtains a better evaporation of the liquid constituents ofthe CBOM, particularly in lowering the partial pressure of suchconstituents. In addition to assisting the evaporation, the presence ofsuch gas appears to be advantageous in preventing undesirable caking atthe CBOM discharge and assists in maintaining an oxygenfree atmospherein the cooling device.

In addition to the above described means for assisting the evaporationof the liquid constituents from the CBOM, the flash-evaporation andsubsequent-heating may be carried out under such conditions as tomaintain a reduced partial pressure of the said volatile constituentsduring the evaporating steps, which condition may be obtained bymaintaining a subatmospheric pressure within the dryer or by passing asuitable inert gas through said dryer by introduction of such a gas at8, and establishing a stream of such gas through and over the dryingblack.

Instead of, or in conjunction with the introduction of an inert gas forthe purpose above outlined, the residual volatile constituents of thecarbon-black may be replaced by a material the presence of which is ofparticular benefit in connection with the use to which the black is tobe put. For example, pine-tar oil, stearic acid or other oils useful inthe compounding of rubber may be introduced to the cooling-down portionof the dryer (cooling-section 32) through the pipe 8, and caused tocontact the black and be absorbed thereby during the downward travel ofthe carbon-black. This feature provides for particularly intimate anduniform mixture of such agent with the black and in this manner-acarbon-black product of highly advantageous characteristics with respectto a particular use may be obtained.

It will be understood that whenever an inert material is introduced withthe CBOM into the dryer, or into the dryer through the inlets 8 or to,the principal proportion of such material will be removed from the dryerthrough the vapor outlet 9 and will pass to the condenser ll with thevapors liberated from the carbon-black or CBOM. If this material becondensible and immiscible with the condensed vapors, it may beseparated from said condensed vapors in the separator i3, while if thismaterial is non-condensi ble at the temperatures and pressures involved,it will pass from the system along with the noncondensible vaporsliberated from the carbonblaek, or if the material be condensible andmiscible with the condensed vapors,-it will enter the oil stream and bereturned to the oil circuit.

through the conduit H. Any treating agent such as pine-tar oil, stearicacid, or the like, which has been introduced to the cooling blackthrough the line 8 and has not condensed on the black in the section 82will pass from the dryer through the outet 9 and thence to the condenserM where it will be caused to enter the oil stream as above described.

The form of apparatus shown in Figs. 3 to 10 is adapted to provide for aconcentration of the CBQM obtained in the dissociation chamber 3 in acombined flash-evaporating and filtering step. The filter portion ofthis form of device is a modification of a continuous filter" such asthat shown and described in reissue patent to J. T. Shimmin No. 18,597,in which a plurality of filter surfaces are arranged to receivespraydischarge $130M and obtain a further concentration by filtration.Referring to the abovementioned figures, the numeral ti! indicates afilter housing rotatably mounted as at 6i and $2 on suitable supportingmeans and provided with rotating driving means 63; the filter housingtil is provided with a plurality of filter sections 66 disposedcircumferentially around the inner periphery of said housing and eachprovided with a suitable supporting structure such as a screen carryinga filter medium such as a woven wire cloth filter surface lit. sections"fa l is provided with connections fill leading from the space behindthe filter support he and connecting to a conduit 68. The severalconduits t8, the number of which corresponds to the number of filtersections 65;, are brought radially inwardly of thefilter housing ti) andlead into an axially projecting housing portion etc and thencelongitudinally of the apparatus to and through a manifold plate 89,which forms an end plate. for the housing portion Gila. A valve plateiii is provided adjacent the plate 69 and a cap member till) is providedon the end of the housing portion 60a adapted to hold the valve plate itinposition with respect to the plate 69. The valve plate is providedwith valve openings mo and 'a'Ob adapted to register with the open endsof the pipes 68 and connections H and H are provided extending throughthe cap member 601) in communication with the valve openings Ella and101), respectively. Connection ii is preferably connected to suitablemeans adapted to provide a liquid suction, and the connection i2 isconnected to means adapted to provide a vapor suction. The cap member601) is preferably so disposed on the housing section Ella as to providea gas-tight seal therewith.-

The CBOM feed line 15 is brought into the filter through the cap member66b, being provided with a suitable stufiing-box as shown at I6, and isprovided within the housing with a radially liquid constituents, andthis layer Each of the filter I 15a having a longitudinally extendingportion 15b disposed at a suitable distance radially inwardly of thefilter sections 64, said section lib being provided with a plurality ofsuitable discharge nozzles 15c directed toward the filter surface ofsaid filter sections 64. The CBOM is delivered from the nozzles 150under a suitable superatmospheric pressure and is sprayed or flasheddownwardly onto the filter surfaces 66 of the adjacent filter section64. As these filter sections pass the nozzles 150 a sucextending portiontion is applied thereto through the conduits 68 which are incommunication with the connection H through the valve openings mo andthis suction will obtain a removal of a portion of the unfiashedliquidcontent of the CBOM, which is drawn ofi through the connection it andmay be returned to the dissociation chamber 8. After the filter sectionshave passed through a suitable proportion of a revolution of the housingtil, for example through argarc such as indicated at F1 in Fig. 9, theconduits G8 are disconnected from the suction line ii and are connectedto the suction line it through the valve opening 3%, and the portion ofthe revolution of the filter indicated at F2 is utilized in the removalof gas from the interior of the filter ti? so as to maintain the sameunder sufficiently low pressure to provide the desiredflash-evaporation. This gas may consist of fixed gases resulting fromthe dissoelation step and vaporized constituents of the CBOM. The abovedescribed filtering operation results in the formation of a layer ofcarbonblack containing a materially low percentage of is removed fromthe filter surface Silas by means of a stripper or scraper Ti and causedto fall into a hopper l8, directed into a screw conveyor l9 and removedirozn the filter into a conduit fit which is directed into the openupper end of a dryer Ell, which may, if desired, be of the same generaltype as that shown at E in Fig. l and Fig. 5. A suitable driving meansis provided for the'screw conveyor it, such as shown at 82, and asuitable vapor duct 83 is provided for the upper end oi the dryer iii,corresponding to the vapor duct t3 shown in Fig. 2, suitable stufimg boxmeans being provided as at til to obtain proper sealing of the rotatingupper end oi the dryer tube with the vapor duct.

n will be understood that suitable sealing means are provided forsealing the screw-conveyor iii to the filten'so that atmospheric air isnot drawn into said filter and mixed with the hydrocarbon and othergases therein. The filter housing at may be provided with an end plate69, and the housing carrying the portions of the screw-conveyor whichare exterior of the filter may be provided with stufing-box means 50" atthe point of passing through said end plate, to effect such sealing. Itwill be further understood that the entire filter housing be rotateswith respect to the conveyor it, and said conveyor passes rotatablythrough the end plate lit and may be rotatably supported at the otherend of said housing as at 1911.

The form of dryer shown in Figs. 11 to 14 is a modification of the formof dryer shown at 5 in Figs. L and 5, and comprises, essentially, arelatively low-temperature heating stage designated as stage i, arelatively high-temperature heating stage designated as stage II, and acooling stage designated as stage III. Stage I o! the dryer may comprisean inclined tube 86 rotatably mounted in a heating chamber 81andprovided with CBOM feeding means at the upper end thereof andcarbon-black discharging means at the lower end thereof. The CBOMfeeding means may comprise a conduit 88 extending downwardly into saidtube througha fixed housing 89 mounted on the upper end of said tube insuch manner as to provide a vapor seal therewith and at the same timepermit rotation of the tube 86; At a suitable point within the tube 86,the conduit 88 may terminate in a CBOM discharge nozzle 88a, such pointbeirig preferably adjacent the upper end of the heating chamber 81. Thelower end of the tube 86 may open into a suitable hopper 9| in positionto discharge carbon-black thereinto, suitable vapor-sealing means beingprovided at the point of entrance of said tube to said hopper, such as astufilng box 92.

The hopper 9I is adapted to deliver carbonblack downwardly into thestage II, which may comprise a tube 93 provided at one end with aportion 94 of reduced diameter, and the hopper 9I maybe provided with aspout 95 opening into the portion 94. The tube 93 is provided with ascrew-conveyor 96 having driving means 91 and adapted to carry thecarbon-black from the portion 94 through the length of the tube 93 tothe other end thereof, at which point a conduit 98 leading to stage D1is disposed. Stage III may comprise a tube 99 provided with a reducedportion I 8| after the manner of the portion 94 of the'tube 93, and theconduit 98 is so disposed as to open into said portion IN. The tube 99is provided with a screw-conveyor after the manner of the tube 93, Fig.14 showing the construction of this conveyor in the vicinity of thereduced portion I8I in greater detail. The screwconveyor may comprise aportion I82 of large diameter fitting within the tube 99 and providedwith an extension I83 of reduced diameter and decreased pitch fittingwithin the portion I8I. The particular arrangement shown is for thepurpose of providing a relatively slow feed of carbon-black from theconduit 98 so that the reduced portion I8I may be maintainedsubstantiaily full of such carbon-black while providing a relativelyfaster feed of such carbonblack through the tube 99, so that such blackwill only partially fill the cross-section of said tube. Theabove-described feeding arrangement is also preferably used between thestages I and II, although it will be appreciated that such specificconstruction is not the only means which may be provided for obtainingthe desired feeding of the carbon-black, but it is an advantageousconstruction in view of the fact that to some extent a vapor seal ispreferably provided between the several stages, for purposes hereinafterdescribed, and the above construction will provide such a seal.

Means are provided for passing a suitable vapor through the severalstages, and such means may comprise a conduit I86 leading into thedischarge end of the tube 99 through which a suitable inert gas may beadmitted, which inert gas will pass through the tube 99 and thenceoutwardly thereof through a conduit I85 connected through a heater I86disposed in the fire-box I81 of the heating chamber 81 tea conduit I88communicating with the discharge end of the tubes 93., A conduit I89leads from adjacent the inlet end of the tube 99. to storage, or otherdisposition. A by-passconduit- H8 is connected into the"iine,l85 at'asuitable point, an d is led into the lower or discharge 'end of the tube86, saidconduit extending through'the hopper 9| and upwardly into saidtube 86 to adjacent the position of the upper end of the heating chamber81 and there terminates in a closed end, for example, as shown at II8bin Fig. 12. The portion of the conduit II8 lying within the tube 86 is 5conduit may be connected to any suitable storage means, such as thegasometer l, as desired. The portion of the conduit lying within thetube 86 is provided with a series of perforations I I2 extending fromadjacent the closed lower end upwardly to a point preferably somewhatabove the point of CBOM discharge. The proportional dimensions of theconduits H8 and III with respect to the diameter of the tube 86 ispreferably such as to allow sufiicient room for the carbonblack todescend through said tube. If desired, the two conduits H8 and III maybe disposed upwardly of the axial line of the tube 86 rather thanaxially of said tube. The two conduits are preferably provided withguard or baflie' means such as a plate H3 disposed over said conduits insuch manner as to prevent accumulation of carbon-black thereon.

In the operation of the form of dryer above described, the tube 86 isexternally heated by heat delivered from thefire-box I81, provided witha burner or the like Ill. The heated gases from the fire-box aredirected to the lower end of the tube 86, as by means of a duct I81a,and are passed in contact with said tube upwardly toward the inlet endthereof through the heating chamber 81, and are discharged adjacent theupper end of said heating chamber through a suitable flue I I6. Theparticular heating arrangement shown herein is for the purpose ofproviding means for progressively increased heating of the tube 86downwardly from the inlet to the discharge end thereof.

Rotation of the tube 86 is obtainable by suitable driving means, forexample such as is shown at ll, 42 and 43 in Fig. 2 in connection withthe dryer 8, and CBOM is supplied through the conduit 88 and dischargedinto the heated and rotating tube 86 at the nozzle 88a. The CBOM isflash-discharged into the tube and the carbonblack is gravitateddownwardly through the tube to the discharge end due to the downwardincli'n'ation and rotation of said tube. The carhon-black is dischargedfrom the tube 86 into the hopper 9| and falls through the conduit 96into the portion 94 of the tube 98, is' carried through said tube 93 bythe action'oi' the conveyor 96 and fed into and carried through the tube99 in the same manner as in the case of tube 93. A suitable inertcooling gas, such as the gas resulting from the dissociation chamber, ispassed at a relatively low temperature into the discharge end of thetube 99 through the conduit I84 and is passed through the tube 99 incounter-current contact with the hot carbonblack. In this contact, thegas is materially heated and the carbon-black is cooled to-packagingtemperature. The cooled carbonblack is discharged from the tube 99 intoasuitable closed hopper I I6,'from which it may be'rernbved as 2,l1d,8dddesired by means of a conveyor M6 to suitable packaging means, notshown.

The inert gas which is passed through the tube 9 in heat-interchangingrelation to the hot carbon-black, is withdrawn from said tube throughthe conduit its and a portion thereof is led through the heater 505 andthence through conduit we to the discharge end of the tube 93, and afurther portion of said gas is passed through conduit lib into the tube88, suitable valve means being provided as at 585a and i052; in therespective conduits m5 and lid whereby the proportional amounts of suchgas are delivered to the desired portions of the apparatus. The portionof the inert gas passed through the heat m5 is heated to a relativelyhigh temperature and is introduced into the discharge end of the tube 93and passed therethrough in heating contact with the carbon-black presenttherein, after which said gas may be delivered through conduit 589 tostorage or other disposition. The portion of the gas passed into thetube 86 obtains a reduction of the partial pressure or" the volatilesreleased from the carbon-black undergoing heating in said tube, and isremoved through the conduit i i i to storage or the like. The gas andvapors withdrawn from both drying tubes 86 and 93 may be introduced tothe conduit 3h (Fig. 1) leading from the dissociation chamber 8, ifdesired, after the manner of the conduit as leading from the dryer 5,whereby condensible vapors may be recovered therefrom and the heateconomies described in connection with the firstdescribed form ofapparatus may be realized.

The flash-discharged carbon-black is subjected to heat appliedexteriorly of the tube 86 whereby the temperature of said black isgradually increased during its downward passage through said tube, andin addition to the heating obtained in the above manner, the heated gaspassed into the tube 86 through the conduit H8 also obtains a degree ofheat-interchange with said black and serves particularly to facilitatethe removal of the principal proportion of the volatiles from said blackby a reduction of the partial pressure thereof. Considerable drying ofthe black is obtained in the tube 86, but it is preferable that thetemperature in this stage be kept somewhat below the maximum-temperaturerequired for complete drying, in order to minimize the formation ofpolymers or cementing materials as above described. For example, thetemperature of the black in stage I may be kept below about 700 or 800R, if desired, so as to provide for evaporation, and removal of themajor portion of the liquid under conditions which preclude heatingthereof to an excessively high temperature, and the black may then beraised to a higher temperature in stage II, under conditions which donot favor the formation of such cementing materials. The gas introducedto stage II at the discharge end of the tube 93 may be at a temperature,for example, of from 1000 to 1300 F. and the carbomblack passing throughthis tube may be thus further heated at an increased temperature and theremaining volatiles removed solely through the agency of thecounter-current stream of gas. In stage III the black may be cooled to atemperature of about 150 C. or lower, e. g. torocm temperature, in thepresence of the inert gas introduced at I04. It will be understood thatthe gas passed in cooling relation with the hot black in stage III andthen passed through the heater I06 may be heated to any desiredtemperature in said heater, this operation cooling the burner gases inthe fire-boa it? so that said burner gases will contact the tube as at asomewhat lowered temperature.

The dry operation is thus seen to be divided into three distinct stages:In stage I, the CBOM is flash-discharged into a heated zone and causedto give up the major portion of its volatiles in the presence of acounter-current stream of gas adapted to lower the partial pressure ofsuch volatiles and assist in the removal thereof; in stage II thecarbon-black is further heated and the final portions oi volatilesremoved therefrom entirely through the agency of a heated gas passedcounter-currently therewith: and in stage III, the carbon-black iscooled through the agency of a counter-current, stream of inert gas andthe thermal energy of said black utilized in raising the thermal energyof said gas, which is further utilized as above set forth.

The carbon-black is thus constantly maintained in an atmosphere of aninert gas, whereby the desirable characteristics of such carbon-blackare preserved. At no time, from the moment oi formation of said blackuntil the packaging there of, is it possible for any deleteriousatmosphere, such as air for example, to come into contact with theblack, and the cooling of the black in the presence of the inert gasatmosphere will cause the black to adsorb and become saturated with theinert gas, whereby there is small .tendency for subsequent adsorption ofany-other vapor or gas, such as oxygen, during subsequent handling ofthe black. We have found that the resulting product, which issubstantially free from adsorbed oxygen, is of superior quality forvarious carbon-black uses, e. g. rubber compounding. The absence ofoxygen in the black decreases the tendency for undesirable oxidationreactions to occur in rubber or other products in which the carbon-blackis compounded with organic materials.

The above drying procedure also provides advantageous economies in fuelconsumption in addition to the economies set forth in connection withthe operation of the dryer 5, particularly in that the sensible heat ofthe hot carbon-black is utilized in heating the treating gas during thepassage thereof through stage III. It will be further appreciated thatany desired type of treating agent may be introduced to the black instage III, such as the above-described pinetar-oil, stearic acid or thelike.

The present invention contemplates operation of a full cycle ofcarbon-black production under such thermal conditions as to produce amaximum quantity of dried and commercially marketable carbon-black witha minimum outlay of electrical and heat energy. This may be carried outby maintaining the temperature and pressure on the dissociation chamberat the highest values consistent with safe operating procedure,utilizing this temperature and pressure to cause evaporation of thecarbon-black oil mixture, recovering the condensible. vapors from theabove mentioned evaporation, and returning such condensed vapors to theliquid supply line. The gas withdrawn from the dissociation chamber iscaused to give up the principal proportion 01' its thermal energy inraising the temperature of the liquid supplied to the dissociationchamben.

As compared to previous methods of electrothermal production ofcarbon-black, the eihciency of the complete disassociatlon and dryingcycle of the present invention is materially increased by virtue of thefact that heat imparted to the liquid undergoing dissociation in thedissociation chamber is more completely retained in such liquid insteadof being dissipated by re-circulation and cooling of said liquid, sothat said liquid is maintained at a materially higher temperature thanhas been hitherto employed. As a result, a smaller proportion of theheat evolved by the dissociation means is consumed in raising thetemperature of the oil from the temperature of the oil body to thedissociation temperature, and

the thermal energy stored in the carbon-black-oil' mixture is utilizedin the subseqent flash-evaporation of the remaining liquid.

In addition to the heat and energy economies made possible by thepresent process, it will be further appreciated that the present processeliminates the objectionable filtration or solvent-extraction steprequired by previously disclosed methods. The advantages in this savingare tremendous from the standpoint of labor, and cost of equipment.

We claim:

1. The method of producing carbon-black which comprises subjecting acarbon-bearing liquid to electrothermal dissociation to cause productionof carbon-black by dissociation of a portion of such liquid, retainingsaid carbon-black in suspension in the remaining liquid, subjecting theresulting mixture of carbon-black and liquid to a flash-evaporatingoperation to cause rapid evaporation of a portion of the liquid contentof said mixture, and recovering said carbon-black.

2. The method set forth in claim 1, and comprising in addition,subjecting said carbon-black to further heating following saidflash-evaporating operation, to cause evaporation of a further quantityof liquid therefrom.

3. The method of producing carbon-black which comprises subjecting acarbon-bearing liquid to electrothermal dissociation to form a mixtureof carbon-black and liquid, maintaining said liquid undersuperatmospheric temperature conditions during such dissociation,withdrawing said mixture from the region of said dissociation,subjecting the withdrawn mixture to a flash-evaporating operation tocause evaporation of a portion of said liquid through the agency of thesensible heat of said liquid and said carbon-black, removing saidvaporized liquid from contact with said carbon-black, and recoveringsaid carbonblack.

4. The method of producing carbon-black which comprises subjecting acarbon-bearing liquid to electrothermal dissociation to form a mixtureof carbon-black and liquid, maintaining said liquid undersuperatmospheric temperature conditions during said dissociation,withdrawing said mixture from the region of said dissociation,subjecting said withdrawn mixture to a fiashevaporating operation tocause evaporation of a portion of said liquid while maintaining themixture under a reduced partial pressure of the vaporized liquid,removing said vaporized liquid from contact with said carbon-black, andrecovering said carbon-black.

5. The method of producing carbon-black which comprises subjecting abody of carbonbearing liquid to electrothermal treatment to causetreating of said liquid and dissociation of a portion of-said liq 'd toform carbon-black in suspension in the remaining liquid, maintainingsaid liquid under superatmospheric temperature and pressure conditionsduring such dissociation, continuing such electrothermal dissociation toproduce a mixture of carbon-black and liquid having a high concentrationof carbonblack, withdrawing said mixture from the region of saiddissociation and discharging the same into a. flashing zone at apressure materially lower than the pressure aforesaid to causevaporization of a large proportion of the liquid therefrom, and

' separating the resulting vapors from said carhon-black.

6. The method as set forth in claim 5, in which the liquid is treatedduring dissociation to a-temperature which would be sufficient to causeat least part of said liquid to boil at atmospheric pressure but inwhich the liquid is maintained under sufiicient pressure duringdissociation to substantially prevent such boiling, and in which saidtemperature is sufficient to cause vaporization of the major portion ofthe liquid from the mixture upon discharge thereof into said flashingzone. 1

'7. The method as set forth in claim 5, in which carbon-bearing liquidis continually suppliedto said body and said mixture'of carbon-black'andliquid is continually withdrawn from said body, the rate of supply andwithdrawal being so controlled as to provide said high concentration ofcarbon-black in said mixture, and in which the major portion of the heatimparted to said liquid by said electrothermal treatment is retainedtherein until said mixture is discharged into said flashing zone so asto furnish the necessary heat for said vaporization.

8. The method as set forth in claim 5, said mixture being dischargedinto said flashing zone at such a rate and under such conditions so asto obtain an incomplete evaporation of the liquid in such mixture in theflash-evaporation thereof and thereby cause formation of loosely-boundagglomerates of carbon-black particles.

9. The method of producing carbon-black which comprises subjecting acarbon-bearing liquid to electrothermal dissociation to producecarbon-black dispersed in said liquid, removing the resulting mixture ofcarbon-black and liquid from the region of such dissociation, thereafterheating said mixture to progressively higher temperature to causevaporization of liquid therefrom, and removing the resulting vaporsduring such heating, separately from the carbon-black and in suchmannerthat said vapors, while in contact with said carbon-black, arecaused to flow only over carbon-black and other surfaces which are at atemperature not higher than the temperature at which said vapors areevolved.

10. The method of producing carbon-black which comprises subjecting acarbon-bearing liquid to electrothermal dissociation to producecarbon-black dispersed in said liquid, subjecting the resulting mixtureof carbon-black and liquid to a flash-evaporating operation to causevaporization of a portion of the liquid therefrom, removing the vaporsthus formed, and then heating the carbon-black and remaining liquid toprogressively higher temperature to cause vaporization of said remainingliquid, while removing the resulting vapors separately from thecarbon-black and in such manner as to avoid heating of said vapors to ahigher temperature than the temperature at which they are evolved,

11. The method of producing carbon-black which comprises subjecting acarbon-bearing liquid to electrothermal dissociation to producecarbon-black dispersed in said liquid, removing the resulting mixture ofcarbon-black and liquid from the region of such dissociation, passingsaid mixture through a heating stage and heating the same while passinga countercurrent stream of inert gas in contact therewith to causevaporization and removal of a portion of the liquid therefrom, and thenpassing the carbonblack and remaining liquid through another heatingstage, and heating the same to a higher temperature than the firststage; while passing a counter-current stream of inert gas in contacttherewith, to. cause vaporization and removal of the remaining liquid.

12. The method of producing carbon-black which comprises subjecting acarbon-bearing liquid to electrothermal dissociation to producecarbon-black dispersed in said liquid, removing the resulting mixture ofcarbon-black and liquid. and subjecting said mixture toflash-evaporation and filtration so as to cause vaporization of aportion of the liq d contained therein and separation of another portionof such liquid in liquid form.

13. The method set forth .in claim 1, said flash-evaporating operationbeing carried out by discharging into a flashing zone at such a rate andunder such conditions as to obtain an incomplete evaporation of theliquid in such mixture in the flash-evaporation thereof and therebycause formation of loosely-bound'agglomerates of carbon-black particles.

14. The method set forth in claim 1, said flashevaporating operationbeing carried out by discharging into said flashing zone at such a rateand under such conditions as to obtain an incomplete evaporation of theliquid in such mixture in the flash-evaporation thereof and therebycause formation of loosely-bound agglomerates of carbon-black particles,and said method comprising in addition, the step of subjecting saidcarbon-black agglomerates to further heating following saidflash-evaporating operation, to cause evaporation of a further quantityof liquid therefrom. V

15. The method set forth in claim 1, said flashevaporating operationbeing carried out by discharging into said flashing zone at such a rateand under such conditions as to obtain an incomplete evaporation of theliquid in such mixture in the flash-evaporation thereof and therebycause formation of loosely-bound agglomerates of carbon-black particles,and said method comprising in addition the step of subjecting saidloosely-bound agglomerates of carbon-black to further heating to removesubstantially all the remaining liquid from said carbon-blackagglomerates, while passing a stream of inert gas in contact with saidcarbon-black agglomerates.

JOHN J. JAKOSKY. VICTOR F. HANSON.

